<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title></title>
  <link href="css/style.css" rel="stylesheet">
  <style>
    body {
      width: 800px;
      background-color: green;
    }

    .banner {
      width: 400px;
      height: 100px;
      background-color: pink;
      position: fixed;
      left: 50%;
      top: 0;
      transform: translateX(-20%);
      z-index: 600;
    }

    .content {
      width: 600px;
      height: 400px;
      background-color: blue;
      position: relative;
      z-index: 500;
    }

    .content:nth-child(2n) {
      background-color: purple;
      z-index: 700;
    }
  </style>
</head>

<body>
  <div class="banner"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
  <div class="content"></div>
</body>

</html>
